• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.286_287
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• 2009

In this paper, the protectability of distance relay is furtherly researched. Based on the probabilistic modeling of the measurement errors, the protectability of three zones is presented in detail by considering their different protection aims denoted by sensitivity and selectivity. The optimal setting for the each zone can be obtained to provide a reference for the practical application.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.442_443
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• 2009

A large wind farm should satisfy the requirements for a grid and accomplish the optimization of the wind farm system. In that point of view, the wind farm intertie protection system, which must consider the Fault Ride-Through (FRT) requirement for more reliable protection, should be improved. This paper proposes a modified distance relay suitable for protection of a wind farm intertie considering a FRT requirement. The frequency change is used to discriminate the intertie fault from a outside zone fault. The performance of the proposed algorithm is verified using a PSCAD/EMTDC simulator.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.676-678
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• 2005

In underground power cable system, the apparent impedance at the relaying point can be changed because of the complicated configuration such as the various earth resistance and the operation of sheath voltage limiter (SVL). They have a bad effect on the distance relay operation Therefore, in this paper, in order to solve this problem, the authors are going to anly the advanced computational technique(ACI) of FR-FIS(Fuzzy Relation-based Fuzzy Inference System).

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.428-429
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• 2008

In a previous paper, the distance relay algorithm for protecting of the underground power cable system was introduced. It effectively advance the errors using ACI(Advanced Computing Intelligence) technique. In this algorithm, the optimization was performed by fuzzy inference system and genetic algorithm. In this paper, hardware system based on ACI technique is introduced and tested by hardware test.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.226-228
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• 2001

this paper presents the distance relay using wavelet transform and least square error method. Wavelet transform detect the faults in the high frequency region and remove the noises in the low frequency region. The variable window length LSE determine optimal window length to each fault case and estimate fault impedance very quickly.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.103-105
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• 1996

This paper describes real time dynamic tests on the digital distance relay using new digital test system including RTDS(Real Time Digital Simulator) in KEPRI. The RTDS is developed by the Manitoba HVDC Research Centre and consists of specialized hardware and software which allows transients simulation of electrical power systems in real time. From high impedance fault test, it is known that the characteristics of distance reach is influenced by load flow. A detailed discussion of relay test using the RTDS simulator, high impedance faults and test results are included in the paper.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.795-802
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• 2007

In the future combat fields, US department of defense (DoD) pursuits the enhancement of the synergy effects of the force through the networking. In specially, the US army force has been emphasized the information superiority for the knowledge superiority and decision superiority of the collaboration force in the Joint Vision 2020, when the operations is performed in the battle fields. In this case study, we are reviewed about the concept of network centric operation and operation case in the centering around the US and analyzed the quantitative distance and effect, performance of communication relay about the distance of mission operation.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2195_2196
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• 2009

DC-offset is a very important subject in power systems protection, since DC-offset causes mal-operation of the distance relay. This paper deals with the influence of a FIR filter used for removing the DC-offset upon the convergence characteristics of distance relaying algorithm based on Fourier Transform.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.12
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• pp.595-601
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• 2000

This paper describes the improvement method of distance relaying algorithm for the underground transmission cables. Distance relaying algorithms have been mainly developing to protect the overhead transmission lines than the underground cables. If the cable systems are directly protected using distance relaying algorithm developed for overhead line without any improvement, there will be really occurred many misoperation in cable systems, because the cable systems consist of the conductor, the sheath, several grounding method, cable cover protection units(CCPUs), and grounding wire. Accordingly, the complicated phenomena are occurred, if there is a fault in cable systems. Therefore, to develope a correct distance relaying algorithm, such cable characteristics should be taken into account. This paper presents the process to improve distance relaying algorithm which is now used. REal cable system was selected to establish modeling in EMTP and ATP Draw. It was discovered through the detailed simulation during the fault that the large error existed between impedance measured at the relay point and real impedance is due to the resistance of grounding wire in each grounding method. And also compensation factor obtained by the simulation is proposed in this paper. It is proved that the factor proposed can fairly improve the accuracy of impedance at the relay point. It is evaluated that the protective ability will be really much improved, if the algorithm proposed in this paper is applied for cable systems of utility.

• Journal of KIISE:Information Networking
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• v.34 no.6
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• pp.423-434
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• 2007

Vehicular ad-hoc network (VANET), a kind of mobile ad-hoc network (MANET), is a key technology for building intelligent transportation system (ITS). VANET is automatically and temporarily established through vehicle-to-vehicle communication without network infrastructure. It has the characteristics that frequent changes of network topology and node density are occurred and messages are disseminated through several relay nodes in the network. Due to frequent change of network topology and node density, however, VANET requires an effective relay node selection scheme to disseminate messages through the multi-hop broadcast. In this paper, we propose a contention window based multi-hop broadcast scheme for VANET. Each node has an optimized contention window and competes with each other for a relay node. The experimental results show that the proposed scheme has a better performance than the distance-based deterministic broadcast scheme in terms of message propagation delay and network traffic.